The present invention relates generally to security systems, and more particularly, to low cost, highly reliable mechanical-electronic locking units. The electronic security devices of the invention physically include a key assembly, a receptacle for the key in a door or other secured device, a receiver for decoding the signal sent from the key, and a novel electromechanical locking-and-unlocking component which is actuated electrically in response to an appropriate signal from the receiver.
Although the concept of electronic locking devices including a key unit capable of sending a coded signal to a receiver to unlock a door or the like are known, prior art devices have utilized various forms of apparatus characterized by a number of shortcomings. For example, in systems which are available at reasonable cost, the keys were easily duplicated because they were relatively simple, and because there were readily available methods of decoding the signal stored in the key. Accordingly, it was easy to duplicate such key and foil the electronic system.
Other units included a coding input apparatus, such as a key or the like, which was extremely delicate, and which accordingly lacked ruggedness and reliability. In still other cases, security systems included keys which, when tampered with, would disable the entire system, causing it to become non-functional after an attempt to tamper with the system had been made, in turn creating significant expense for the owner in repairing a system which had been tampered with.
Other units intended for this general purpose have required multiple signal paths for coding or synchronizing the operating of the key and the receiver. In certain of these prior art units, there would be, for example, three signal paths within the system, one path being dedicated to coding, or data, one being dedicated to synchronization or clocking, and the last to clearing or resetting.
Where signal transducers are required, such as optoelectronic or optomagnetic transducers, multiple signal path requirements made these units costly and unduly complex.
Other electronic locking devices require that the operator remember and enter a lengthy sequence or combination of numbers in order to enable the lock to be opened. Consequently, systems of this sort are not suitable for use by small children, are inconvenient for adults, and are not suitable for use by those who have difficulty remembering arbitrary numbers.
Still other prior art units are disadvantageous because they require power in the key, because they consume significant power in the code processing operation, or in the locking and unlocking operation. Still other systems have been devised which, while satisfactory in some respects, were excessively costly, or were not compatible with additional security features sought to be used with the lock, such as burglar alarm systems, fire detecting systems, etc.
Accordingly, in view of the shortcomings of the prior art, and the need for a simple, low cost highly secure electronic locking system, it is an object of the present invention to provide an improved electronic security system.
Another object of the invention is to provide an electronic security system of an improved character which includes a key unit, and a lock unit comprising a key receptacle, a decoder unit, a power supply, and an improved electromechanical, three position lock unit.
A further object of the invention is to provide a system which will overcome some or all of the drawbacks associated with the previous attempts to provide satisfactory electronic locks.
Still another object of the present invention is to provide an electronic security system using a key which is sufficiently complex to prevent duplication, but which is extremely low in cost compared to counterpart devices.
Another object is to provide an electronic system using a pair of integrated circuits which are internally identical, but which possess different external circuit components, with onecircuit being utilized in the key or transmitter, and the other being used in the decoder or receiver.
Another object is to provide a key-and-lock unit in which a predetermined unlocking code is sent continuously from the transmitter, received and decoded by the receiver, and if satisfactory, sends a signal which operates to energize a relay causing the lock to be opened.
A still further object is to provide an electromechanical locking system having novel and improved mechanical components, and more particularly, having a combination latch and lock which may operate in an open position, a dead bolt position and a preset intermediate position, and which is adapted to be moved between these positions either manually by the operator or electrically.
Another object of the present invention is to provide an electromechanical lock for use in an electronic security system wherein the lock is able to be moved from a locked to an unlocked position with minimal use of electrical energy, and which, if preset, will automatically move to a dead boltlocked position when the secured device is closed.
Another object is to provide an electronic key and lock system which is readily adaptable for use with electronic security components, such as burglar alarms, fire alarms, etc., and which is able to provide additional auxiliary functions without significant increase in cost.
A still further object of the invention is to provide an electronic lock system including a circuit having a programming pin which allows another copy of the receiver integrated circuit to function as a transmitter or key.
Yet another object of the invention is to provide a tamper proof enclosure for the key, whereby the security thereof cannot be compromised without destroying the key, and which will resist even determined attempts to compromise or foil the system.
Another object is to provide a low power-consumption system which is adapted to be energized by a variety of power supply systems.
Another object is to provide a coding and decoding electronic system wherein the frequency as well as the count of pulses may be varied so as to provide additional combinations and to increase security without measurable increase in cost.
A still further object is to provide an electronic security system which is convenient and compact in use, and which does not require the key or transmitter element to be self-powered, but which allows power for the operation of the key to be obtained from the receiver when and only the key is in place in the receptacle.
Another object of the invention is to provide an improved electronic security system wherein the pulsed code may be transmitted in the infrared spectrum by means of a fiber optic "light pipe" to the receiver unit, thereby providing additional security in relation to systems using electrical signal paths only.
Another object is to provide an improved system which is not susceptible to electromagnetic tampering, by reason of using a coded infrared optical signal pulse stream as the code.
Another object is to provide an improved electronic security system having a receiver which is effective to receive a series of coded pulses, to preset a counter at the beginning of a sequence of pulses, to count the incoming pulses, compare the number of incoming pulses with the predetermined code in the counter, and to energize an unlocking device if the number of pulses is identical and to disable the unlocking device if the number of pulses is not identical.
A still further object is to provide a lock and key apparatus wherein advantageous use may be made of semi-custom integrated circuitry so as to reduce the cost and improve the reliability and compatibility of the key and lock electronics.
Yet another object is to provide a combination electronic lock and key unit which includes semi-custom integrated circuitry in both the key or transmitter unit and in the receiver unit, with the circuitry being modified slightly by differing external components and connections so that otherwise identical components can perform different functions in their respective assemblies.
A still further object is to provide an electronic lock and key unit in which a single stream of clocked pulses is interrupted periodically for a definite interval to subdivide a continuous pulse stream into a series of periodic pulse streams each having a predeterminable code number of pulses, and which further includes means for transmitting the coded pulse stream to a receiver, comparing the number of pulses in the coded stream to a predetermined code number in the receiver, and for energizing an interlocking device in response only to reception of a stream of pulses having the identical coded number of pulses therein.
A still further object is to provide a key unit which includes special physical as well as electronic features, including an optical filter, a light pipe arrangement, and semicustom integrated circuitry, a transformer secondary circuit core and a magnetic coupler, all in a compact, sealed unit.
The foregoing and other objects and advantages of the invention are achieved in practice by providing a key unit which includes an oscillator component for emitting a stream of constant-width pulses, and a unit for interrupting the stream to create an open space between each stream of pulses, whereby a series of streams each having a predeterminable number of pulses therein are transmitted to the receiver in the form of infrared light signals. The stream of light signals is received, transduced and amplified, and sent to a decoder unit, which includes a counter adapted to go to a predetermined logic state when filled; and circuits arranged to determine whether the counter is filled simultaneously with the arrival of the blank space between coded transmissions. This latter circuitry includes a digital logic arrangement requiring coincidence of a carryout pulse from the counter and the blank space between transmissions, using this coincidence to energize a relay for unlocking the secured device. In a preferred form, the transmitter or key is unpowered until placed within the receptacle, whereupon magnets in the key energize the receiver unit and transmit power through an inductive circuit to the key, causing the transmitter and receiver elements to achieve proper initial states and then perform the sequence of sending an encoded transmission, decoding it, and unlocking it as described herein.
The manner in which these and other objects and advantages of the present invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments set forth by way of example and shown in the accompanying drawings in which like reference numbers indicate corresponding parts throughout.